The Cool Energy House

by Andrew Hunt On Dec 7, 2011

Demonstration homes are a staple of the International Builders’ Show, and in February 2012 in Orlando, Fla., visitors will have a chance to see not only new construction projects, but also take a tour of a home that was remodeled in an innovative and non-intrusive way. The Cool Energy House, a show home produced by the Washington, D.C.-based U.S. Department of Energy’s Building America Retrofit Alliance (BARA), will demonstrate how to take an existing home and improve energy efficiency by nearly 50 percent with little disturbance to the home’s charm and existing features.

The Team and House

BARA is one of the Building America teams charged with developing innovative, real-world solutions that achieve significant energy and cost savings for homeowners and builders. For more information about Building America and the BARA team, visit ForResidentialPros.com/BuildingAmerica to read “What Is Building America and the Building America Retrofit Alliance?” by Stacy Hunt and Craig Savage.

This remodeling project was selected by BARA because of its comprehensive nature and the opportunity to interject significant energy improvements in a “traditional” remodeling process. The remodeling work is being paid for by the homeowner with technical and communications support provided by DOE’s Building America program and other project contributors.

The Cool Energy House was built in 1996, a time when energy efficiency was just beginning to gain ground but was still not a major concern during the design and construction of new dwellings. However, the project is not just about gaining efficiency. “This project is really about showing affordability, not just possibilities,” says Craig Savage of Building Media Inc., a Seattle-based provider of online training programs for the construction industry and part of the BARA team.

The 3-story, 3,600-square-foot, four-bedroom brick house features a full-width second-story veranda overlooking a pool. The first floor walls are 2- by 6-wood frame, and the second and third floor walls are 2- by 4-wood frame. The third story of the home is divided between finished and unfinished attic space.

The homeowners requested an addition consisting of a three-car garage with a live-in unit above the garage. The homeowners employed architecture firm Winter Park Design Inc., Maitland, Fla., to design the remodel and addition, and Orlando-based Southern Traditions Development, a custom-home builder focused on home performance, to complete the renovations.

Building-envelope Improvements

As a first step, an initial energy audit was conducted by another Building America team, the Consortium for Advanced Residential Buildings. The audit revealed fair to poor insulation in the exterior walls, resulting in an R-value between 10 and 12 in the first-floor walls and an R-value between 7 and 9 in the second- and third-floor walls. The ceiling areas had 4 to 6 inches of filthy blown fiberglass insulation, resulting in erratic R-values between 15 and 18. Substantial gaps between the insulation and the wall frame also were noted. These gaps allowed airflow inside the walls.

Windows were aluminum-framed, double-paned in most of the house with the exception being the single-pane windows on the lower back of the house and leaky wood French doors.

Once the building was evaluated, all the data gathered about the home’s current energy use was entered into BEopt, the DOE’s Building Energy Optimization software that rapidly does building costs versus energy-savings analysis. The software analyzed the data and generated a report of various home improvements specific to the climate. Anyone can download and use BEopt by visiting beopt.nrel.gov.

BEopt is especially helpful in retrofit projects because, according to Savage, “It essentially allows you very quickly to determine in your area what energy efficiency measures to apply to your home to get the biggest bang for your dollar.” These measures include insulating, air sealing and duct sealing. Building America is producing guidelines for these measures at a rapid rate to help support builders and remodelers as the learn how to make projects more energy efficient.

A common problem often encountered during energy-efficient retrofit projects is minimal or inadequate existing insulation in the walls. In this case, fiberglass batts were improperly installed in the wall cavities, providing reduced R-value. Short of removing the interior drywall, which can be very invasive, time-consuming and costly, there are few options available to retrofit contractors. However, a new technique is being tested to improve the insulation and air-sealing properties in the walls at the Cool Energy House. JM Spider insulation from Johns Manville, Denver, is a blown-in fiberglass insulation coated with a water-based adhesive and was chosen for the home.

Ten-inch wide bands of drywall were removed at 4-foot intervals,and holes were drilled under and over windows in the interior walls, allowing a hose to be fed into the wall cavity. The insulation was blown into the space in the stud cavities. It collapsed the ill-fitting fiberglass batts and literally stuffed itself in the entire wall cavity, which should slow air movement in the stud bay.

In the attic, an R-30 layer of closed-cell spray polyurethane foam insulation was applied to the underside of the existing roof deck. The strong, dense foam not only improves the energy efficiency, but also helps the roof survive a hurricane. The insulation essentially glues the roof components together, preventing roof uplift. A study titled, “Improving the Wind Uplift Capacity of Wood Roof Panels Retrofitted with ccSPF Adhesives,” showed roofs treated in this manner were able to withstand air pressures in excess of 153 psf or roughly the wind speed found in a category 4 hurricane. (Read the study at DavidOPrevatt.com/wp-content/uploads/2010/01/ncfi-report-oct-2007.pdf.)

Closed-cell insulation also was chosen instead of open cell because of its impermeability. Especially in Florida’s climate, open-cell insulation can allow the migration of moisture allowing mold-friendly condensation between the foam and the roof deck.

Additional Efficiencies

Windows are another major culprit in energy and cooling inefficiency. Although some of the doors and windows were energy efficient, the BEopt report indicated it was worth the effort and cost to replace the first-floor back-of-the-house single-pane aluminum windows and leaky French doors. However, the double-wall, brick-veneer construction presented an installation challenge. The team had to determine how to retroactively flash the window openings to prevent moisture migration into the building envelope

The owner wanted the replacement windows to look like the originals, so the builder had to flash and install them at the interface between the brick veneer and the framed wall. The solution was to wrap the entire rough opening with a butyl flashing tape and then secure and caulk the “block frame” window unit in place, covering the tape with a snap-on window trim. (See the photos.)

More upgrades were made throughout the house, such as new Energy Star appliances, a variable-speed pool pump to replace an aging single-speed pump and LED lighting upgrades to complement the overall lighting redesign. New energy-efficient bathroom fans also were installed.

Follow Along

As the project moves into the final stages of completion, BARA and Qualified Remodeler hope you follow its progress by visiting ForResidentialPros.com/BuildingAmerica. The web page showcases articles and videos designed to educate remodelers and the general public about innovative, cost-effective ways to improve an existing home’s energy efficiency based on what was done at the Cool Energy House. Best of all, the Cool Energy House is a classic example of a complete energy-efficiency retrofit where from the outside nothing seems different, but from a comfort, durability and utility-bill perspective it is a whole new home.

Andrew Hunt is principal with Missoula, Mont.-based Confluence Communications, a company that serves businesses involved in energy-efficient and environmental construction. Confluence Communications also is a member of the Building America Retrofit Alliance